Kawasaki Z900RS (2018) | Review

ByJohn Milbank

BikingMilbank BikeSocial Consumer Editor, John owns a KTM 1050 Adventure. He's as happy tinkering in the workshop as he is on twisty, bumpy backroads, and loves every bike ever built (except one). He's bought three CBR600s, two Ducati Monsters, several winter hacks, three off-roaders, a supermoto pit bike, a Honda Vision 50 and built his own custom XSR700.

“They don’t make ’em like they used to.” No, they don’t… and let’s celebrate that.

Kawasaki’s new Z900RS is described as an homage to 1972’s Z1, the most powerful Japanese four-cylinder bike of its time. This is not meant to be a copy, and for good reason, but I’d describe it as something more than an homage; I’d call it an evolution.

The first 100 yards on this machine stuck with me – I was expecting a mild-mannered retro bike, not the instant, eager throttle response and light, fast steering I experienced as we sped away from the launch hotel. I shouldn’t have been so surprised of course, as the Z1 was the high-performance sportsbike of its time, and while the Z900RS won’t worry the ZX10R, it makes more power and torque through the low to mid-range than the Z900 that donated its motor, and that’s far more useful away from the track.

Compared to the Z900, the RS’ cam profiles give a shorter lift duration, while compression is reduced from 11.8:1 to 10.8:1 and the header pipes have a reduced internal diameter, all of which contributes to the increase in power and torque below 7000rpm. The flywheel’s also 12% heavier

This is no flat-bar rehash of a Z900. While the motor is fundamentally the same, and the frame bears a passing similarity, that’s about it. The Z900RS’ styling designer, Norikazu Matsamura, started the design with the teardrop tank, then worked out the rest from there. As this engine uses a downdraft fuelling system, getting any kind of useful capacity was a challenge – in the end, the new bike has a 17litre tank, compared to the 18litres of the original, and it’s been achieved by allowing the tank to continue down behind the side panels; very clever, though something that Matsamura-san told me was “very difficult to make.”

Besides a new frame, the bars are 30mm wider, 65mm higher and 35mm closer to the rider than on the Z900

So while the frame’s rails are the same thickness up front as on the Z900, they had to be moved to accommodate the tank, but there are other changes too – the swingarm pivots are housed in pressed steel plates now, as opposed to the tubes with plastic covers of the Z900, while the tail section is flatter. Here, thicker tubes were used than on the Z9, as the more horizontal orientation made it harder to control vibration than on the sports naked.

While the bars are rubber mounted, and the pegs have rubber inserts, this motorcycle hasn’t been sanitised – there’s still enough of a buzz to feel the engine working, but nothing that’ll distract or annoy. At 75mph in sixth gear, the motor’s spinning at a comfortable 4,500rpm (the limiter’s at 10,500); only up at around 6,000rpm do you start to feel a buzz through your pants. And don’t expect authentic vintage shakey mirrors – while these have been designed to echo the Z1, Kawasaki’s engineers have also aimed to minimise vibration. They were successful.

First gear is shorter on the RS than the Z900, while top gear and the final drive are longer

What’s it like to ride?

Regardless of the intentions behind this bike, it’d be pointless if it handled like a 1970s machine. It doesn’t: the steering’s quick, but it’s also accurate; the suspension is firm but compliant – deliberately aiming for bumps it wouldn’t kick me too hard, and it’d stay in shape at speed, so the most I could get it to do was rear up slightly and briefly shake the bars as I dived through a hidden dip in the road. It felt alive, but it felt in control.

The brakes are typical Kawasaki – powerful enough for one-finger control, but without being sharp or aggressive; the radially-mounted Monobloc calipers are connected by rubber hoses to the radial master cylinder, and perfectly compliment the fully-adjustable front forks.

The brake and clutch lever are both adjustable – another nod to the higher quality kit used on this bike

The back has a single shock, adjustable for rebound damping and preload, while the wheels – shod in Dunlop GPR-300s – are cast, with a machined finish that sees the rims and ‘spokes’ exposed through the black paint.

It’s comfortable too – those high bars and the plentiful space between the 835mm-high seat (there’s a 35mm lower option too) and 20mm further forward and higher up than the Z900 pegs combine with a well-padded seat to make a day in the saddle a welcoming prospect. I’m 5’10” and had no problems riding or getting my feet flat on the floor, but even 6’4” journalist Roland Brown said he was very happy with the riding position. It’s confidence-inspiring, and that plentiful low-down torque also makes the RS very easy to turn around in the road – there’s no risk of stalling it even as you take full advantage of the reasonably generous 35° of steering lock.

Despite the lack of a fairing, it’s easy to imagine covering plenty of miles on this bike thanks to the well-designed riding position. The 17litre tank would give a range of up to 165 miles given the 45mpg I returned during the launch. I tend to be quite heavy handed, but the best recorded during our fast ride was 48mpg, so expect to fill up around every 150 miles, to be on the safe side. You won’t get much besides a disk lock under the seat (or Kawasaki’s own U-lock), though there is a 12V socket under there, and the key-hole, which is under the tail, has a sturdy rubber cover to keep the muck out.

Kawasaki’s own U-lock is designed to fit under the seat – a good nod towards the need for security…

The engine drives seamlessly right the way through its rev range – no flat spots, no peaks, just constant drive that’ll see you bouncing off the limiter if you’re really pushing on, but the transition from off to on has a disconcerting step. It’s a common trait of many fuel-injected bikes (potentially made worse by the lean mixtures demanded by Euro 4), and here I noticed it most on the tight mountain sections of our test ride in second gear, particularly when riding fast; as I’d open the throttle after braking hard for a corner, there’d be a fraction of a second’s delay before the engine picked up again. It’s not dangerous, and if you’re very smooth with the throttle you can pretty much eliminate it, but if you’re constantly on and off the gas, that snatchy feel can be a little off-putting.

The best way to avoid this trait is to ride in a gear higher – the 72.6lb-ft of torque is so well spread that you don’t need to ride aggressively. You don’t need to keep hammering up and down the slick, smooth gearbox (which welcomes clutchless upshifts) – just use the grunt of 110bhp engine to pull you through the really tight stuff, then wind it on harder as the roads open up.

If you are working the ’box, whether it’s for a spirited pace or simply in town, you won’t get tired – the slip/assist clutch helps prevent the rear end locking up if you knock down too many cogs, but the design, which has cams to pull the plates tighter together under load, means lighter springs can be used, resulting in a much easier pull on the cable-operating lever.

A slip-assist clutch has a cam shape that pulls the plates tighter together under load from the engine, but pushes them apart when the wheel is applying more torque than the motor

Being a modern bike, the RS does of course have all that new-fangled electronic malarkey. “They didn’t do that in the old days – our wrists were our traction control.” I actually like having quality ABS on a bike (it’s Nissin kit on here), and unlike the relatively sparse Z900, the RS also has two levels of traction control. You can switch it off, but the system, which looks at wheel speed and the bike’s position relative to the road, not just to horizontal, can cope with different tyre profiles, wear, and road camber.

In mode one, it alters the ignition timing to allow a limited amount of slip. In mode two, timing, fuel and air flow are all governed to cope with more slippery roads. In practice, while mode 2 will stop the front wheel lifting almost instantly, and keep the bike under control on Spain’s notoriously slippery white road paint, it does so without feeling intrusive. The ECU will remember which mode the bike was in when you took the key out, though if the traction control was turned off, it’ll be in mode one when you fire the machine up again.

The new bike’s exhaust note has been tuned – it’s most noticeable at idle, where there’s a deeper bass note, or when you’re riding between buildings

They don’t make them like they used to. Now they make them handle better, they make them faster, they make them more comfortable and they make them lighter (31kg lighter in this case). The definition of a sportsbike might have changed over the last 35 years, but if Kawasaki had the materials analysis and advanced technology of today, I’m pretty sure the Z1 would have looked and ridden very much like the Z900RS, and I’d much rather hack around my local roads or tour across Europe on this, than what we call a sports machine today…

Key nods to the Z1

Besides being obsessed by cacti – “it’s such an aggressive plant” – the Z900RS’ styling designer, Norikazu Matsamura, owns a Kawasaki Zephy 750 D1 that he customises as a hobby. He’s designed 26 bikes during his career, some of the most notable being the Z750, 2005 ZX-6R, first generation Versys, 2008 ZX-10R, the W800 and the Ninja H2. He took us through some of the key design touches he brought from the original Z1 to his latest creation…

The paint of the flagship Candytone bike we’ve tested is of course reminiscent of the Z1, but the finish was a challenge due to the lack of the carcinogenic paints that were used in the ’70s. The graphics are effectively waterslide transfers, which don’t leave a bump under the lacquer like vinyl.

Analogue clocks were a must for this bike, but the styling goes deeper than simply two dials – the typeface used for the numerals is the same as that on the 1972 machine, and even the centres of the needles have the same flat top and chamfer of the original.

While the engine is clearly a modern powerplant, fins and cam cover details have been machined in as a nod to the Z1. The side cases have also been updated since this motor was used in the Z900 to closer echo the original – while it’s no exact match, the shape of the clutch cover, for instance, is designed to follow the lines of its older brother.

The mirrors are unique to this bike, echoing the shape of the old machine, though here they’ve also been designed to not vibrate.

Matsamura-san told me that “many discussions” went into the idea of using spoked wheels on this bike, but ultimately the decision was made to use cast wheels for their weight advantage, ease of cleaning, and their lack of a need for maintenance.

The only similarity really with the exhaust to the original is the shiny finish. Here it’s high-quality stainless steel, instead of the original chromed item that enthusiastically rusted away. While purists will likely argue, the original’s huge seam running along the edge really wasn’t that attractive. When I asked if there was one thing Matsamura-san really wanted to design into the Z900RS, but was unable to, he told me it was the exhaust; “I wanted to have a twin-pipe design,” he said, “but only on one side. In the end though, we wanted to reduce weight, so chose a single end-can.” Kawasaki says that this also ties in with the company’s desire to make a machine that was a high-performance version of the Z1 – many owners of the bike used to whip the old pipes off and fit a four-into-one, and would also often swap for mag wheels.

The original machine’s exhaust system looked great. From a distance. Until it rusted away

The original’s side panels had a bulge on the leading edge to accommodate the carb intakes, and it’s seen here too, over the aluminium trim panel and frame spar.

The tail unit went through many iterations before Matsamura-san was happy – it had to have that distinctive flick at the rear.

The taillight is oval, to echo the Z1, and while it uses LEDs to illuminate it, they’ve been laid out to mimic the glow of a bulb.

While this is a full LED headlamp, the daytime running lights are designed to make it illuminate fully – like the original. It’s round, of course, but look at it from the side and you’ll see that the convex lens has a very similar radius to that of the 1972 machine.

The seat has moulded faux-stitching on the top, but the sides really are stitched in place. More importantly, the pillion strap is held with D-shaped metal clasps, fixed with a cross-head screw. Matsamura-san actually tried hard to track down the original manufacturer of that screw, but the thread pitch was no longer available.

Look closely at the ‘Z900RS’ badge on the side panels and you’ll see a stippled effect under the white paint – this mimics the stippling in the Z1’s badge, which is notably missing from most replica badges as it’s so hard to replicate. Also, cover the ‘RS’ portion, and the badge mirrors the Z900 A4 of 1976.

But why no twin shocks?

The exhaust and wheel designs were chosen to give the bike the best possible weight and handling advantages, and the same goes for the shock (a desire for modern, refined and effective suspension is the reason right-way-up forks weren’t even considered). Using a progressive link and single shock, Kawasaki was able to give much better handling, not only due to the control offered by this design, but by mass-centralisation that comes from pushing components closer to the centre of the bike.

Get off the RS and onto the original Z1 and you can feel the 31kg extra that the old bike carries. Looking at the RS as an evolution of the original, the decision makes sense, and as one journalist at the launch put it; “If you really want the authentic handling of the old twin-shock bike, just let the tyres down.”

Z900RS Cafe

The Cafe model, which will cost £10,349, is not simply a repainted RS with a cowl – the headlight is repositioned to put the cowl in the correct position for the horizontal sweep that Matsamura-san was looking for, the bars are lower, the mirrors are lower and closer together, and the seat has been redesigned to hint at a single-seat design without sacrificing practicality.

But you’ll also notice the different wheels, which closer echo the mags that many used to fit to the Z1, a satin-finish exhaust, and the black details on the engine and rad guards. Oh, and a ‘DOHC’ badge on both sides of the engine that we really hope can be bought as an optional extra on the RS.

The competition

Kawasaki sees the main competitor to this machine as being the BMW RnineT, which starts at £10,000 for the most basic ‘Pure’ model. Other machines in the Japanese company’s sights are Yamaha’s £8,699 XSR900, and the Ducati Scrambler, which starts at £10,695 for the new 1100 model.

The target audience for the RS is said to be between 35 and 55 – with the average age of Kawasaki’s UK customers being 52 (many of whom will fondly remember the Z1) and the high number of pre-orders taken in November, sales are expected to be high.

The exhaust on this bike is a twin-walled, fully stainless steel system. This means the downpipes shouldn’t discolour unpleasantly, and it’ll last. It’s a one-piece design to where the end-can connects (an Akrapovič is available as an option), so if you insisted on de-catting the Z900RS, you’d need to replace the lot

Specifications: Kawasaki Z900RS

Engine

948cc liquid-cooled DOHC four-cylinder (Z1 was 903cc air-cooled)

Power

110bhp (82kW) @ 8,500rpm (Z1 made 81bhp)

Torque

72.6lb-ft (98.5Nm) @ 6,500rpm (Z1 made 54.2lb-ft)

Bore x stroke

73.4x56.0mm (Z1 was 66x66mm)

Frame

Tubular diamond with extruded aluminium swingarm

Front suspension

Fully adjustable fork

Rear suspension

Single shock adjustable for rebound damping and preload (Z1 had twin shocks)

Front brakes

2x267mm discs with radially-mounted four-piston Monobloc calipers and radial master cylinder (Z1 had one 290mm disc with a single-piston caliper, but the option of a second disc and caliper on the right, though the master cylinder had to also be replaced for it to work properly)